Tuesday, July 24, 2012

Lately I keep running into the idea that the proper way to do science is to continually strive to disprove a hypothesis, rather than support it*. According to these writers, this is what scientists are supposed to aspire to, but I've never actually heard a scientist say this. The latest example was recently published in the Wall Street Journal (1). This evokes an image of the Super Scientist, one who is so skeptical that he never believes his own ideas and is constantly trying to tear them down. I'm no philosopher of science, but this idea never sat well with me, and it's contrary to how science is practiced.

Sunday, July 22, 2012

My colleagues Drs. Mario Kratz, Ton Baars, and I just published a paper in the European Journal of Nutrition titled "The Relationship Between High-Fat Dairy Consumption and Obesity, Cardiovascular, and Metabolic Disease". Mario is a nutrition researcher at the Fred Hutchinson Cancer Research Center here in Seattle, and friend of mine. He's doing some very interesting research on nutrition and health (with an interest in ancestral diets), and I'm confident that we'll be getting some major insights from his research group in the near future. Mario specializes in tightly controlled human feeding trials. Ton is an agricultural scientist at the University of Kassel in Germany, who specializes in the effect of animal husbandry practices (e.g., grass vs. grain feeding) on the nutritional composition of dairy. None of us have any connection to the dairy industry or any other conflicts of interest.

The paper is organized into three sections:

A comprehensive review of the observational studies that have examined the relationship between high-fat dairy and/or dairy fat consumption and obesity, metabolic health, diabetes, and cardiovascular disease.

A discussion of the possible mechanisms that could underlie the observational findings.

Differences between pasture-fed and conventional dairy, and the potential health implications of these differences.

Thursday, July 19, 2012

In the comments of the last post, we've been discussing the relationship between body fatness and diabetes risk. I think this is really worth understanding, because type 2 diabetes is one of the few lifestyle disorders where 1) the basic causes are fairly well understood, and 2) we have effective diet/lifestyle prevention strategies that have been clearly supported by multiple controlled trials.

Thursday, July 12, 2012

Aitor Calero writes for the popular Spanish cooking and nutrition blog, Directo al Paladar ("straight to the palate"). We did a written interview a while back, and he agreed to let me post the English version on my blog. The Spanish version is here and here.

Sunday, July 1, 2012

As discussed in the previous post, a recent study by Dr. David Ludwig's group suggested that during weight maintenance following fat loss, eating a very low carbohydrate (VLC) diet led to a higher metabolic rate (energy expenditure) than eating a low-fat (LF) diet, with a low glycemic index (LGI) diet falling in between the two (1). The VLC diet was 30 percent protein, while the other two were 20 percent. It's important to note that these were three dietary patterns that differed in many ways, and contrary to claims that are being made in the popular media, the study was not designed to isolate the specific influence of protein, carbohydrate or fat on energy expenditure in this context.

Not only did the VLC diet lead to a higher total energy expenditure than the LF and LGI diets, the most remarkable finding is that it led to a higher resting energy expenditure. Basically, people on the VLC diet woke up in the morning burning more energy than people on the LGI diet, and people on the LGI diet woke up burning more than people on the LF diet. The VLC dieters burned 326 more calories than the LF dieters, and 200 more than the LGI dieters.

It's always tempting to view each new study in isolation, without considering the numerous studies that came before it, but in this case it's essential to see this study through a skeptical lens that places it into the proper scientific context. Previous studies have suggested that:

The carbohydrate:fat ratio of the diet has little or no detectable
impact on energy expenditure in people who are not trying to lose weight (2, 3).

The carbohydrate:fat ratio of the diet has little or no detectable
impact on energy expenditure in people who are being experimentally overfed, and if anything carbohydrate increases energy expenditure more than fat (4, 5).

The carbohydrate:fat ratio of the diet has little or no detectable
impact on energy expenditure during weight loss (6, 7, 8), and does not influence the rate of fat loss when calories are precisely controlled.

This new study does not erase or invalidate any of these previous findings. It fills a knowledge gap about the effect of diet composition on energy expenditure specifically in people who have lost weight and are trying to maintain the reduced weight.

With that, let's see what could have accounted for the differences observed in Dr. Ludwig's study.

About Me

I'm a writer and science consultant with a background in neuroscience and obesity research. I have a BS in biochemistry and a PhD in neurobiology. I'm the author of "The Hungry Brain: Outsmarting the Instincts That Make Us Overeat".

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Disclaimer

This blog is a compilation of my opinions. It's not advice; it's information that you can take or leave as you please. I don't intend it to replace professional medical consultation or treatment. Your health is in your own hands.